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How air pollution can cause cancer

Air pollution increases the risk of lung cancer. For each individual person, the increase in risk of cancer is small. But because everyone is exposed to some air pollution, when we think about big numbers of people, like the population of a country, air pollution has a much bigger effect.

And air pollution isn’t only linked to lung cancer, there is also good evidence that it can increase the risk of other diseases, mainly respiratory diseases and heart disease.

However, it’s important to keep the risk in perspective. Smoking has a much bigger effect on the risk of developing lung cancer than air pollution.

What is air pollution?

Air pollution is the harmful things that are found in the air we breathe.

It is a mixture of many different substances and the exact contents vary depending on its source, your location, the time of year and even the weather. Air pollution can be man-made, such as fumes from cars and smoke from burning fuels like wood or coal. But it also includes natural substances, like desert dust that travels to the UK all the way from the Sahara desert.

Air pollution is often separated into outdoor and indoor air pollution. Both indoor and outdoor air pollutants have been shown to increase the risk of cancer. Air pollution is associated with an increased risk of lung cancer. Although the increased risk of cancer is small for individuals, because everyone is exposed to some air pollution, it has an important effect across the population as a whole.

Outdoor Air Pollution

In 2013, outdoor air pollution was identified as a cause of cancer by the International Agency for Research on Cancer (IARC). It’s responsible for far fewer cases of cancer than other risk factors, such as smoking and obesity, but air pollution affects everyone.

The research shows that tiny dust-like particles - called ‘particulate matter’, or PM – are an important part of air pollution. The smallest particles – less than 2.5 millionths of a metre across, known as PM2.5 – appear to be behind lung cancers caused by pollution.

The risk of developing lung cancer increases as the level of PM2.5 in the air increases.

How big is the risk in the UK?

Compared to other countries around the world, the UK has fairly low levels of air pollution. For most pollutants it is within the EU limits.

Because levels of PM2.5 are relatively low, the increased risk for an individual is fairly small. The exact risk depends on how much air pollution people are regularly exposed to. But it’s hard to say exactly what the risk is for the people living in a certain area.

Overall, almost 1 in 10 lung cancer cases in the UK are caused by exposure to outdoor air pollution.

Another thing found in air pollution is nitrogen dixoide. The UK, and particularly cities, are in breach of EU commitments on nitrogen dioxide (NO2) which we sometimes hear about in the news. But it isn’t completely clear whether NO2 could directly cause cancer. You can find out more about air pollution levels in different regions of the UK on the UK-AIR website.

What can I do?

It’s difficult for anyone to avoid air pollution completely. But there’s no need to shut yourself away because pollution levels in the UK mean that generally this risk is very small.

As individuals, we can play our part in reducing air pollution levels by trying to avoid creating more of it. Choosing ‘active travel’ options where possible, like walking and cycling, can help reduce pollution levels from transport and is also a great way to be more active, which has lots of health benefits both for cancer and other diseases.

Everyone has a right to be healthy. Cancer Research UK wants to see Government and local authorities working together to develop a comprehensive strategy to reduce outdoor air pollution to protect people’s health. It’s important to keep this risk in perspective; most lung cancer cases are still caused by smoking. But as we work towards a tobacco-free UK it's important to look at what else we can do to help minimise the risk of cancer.

Indoor air pollution

Indoor air pollution can have many sources, including fuels used to heat homes and cook with, and tobacco smoke. In the UK, the most common type of indoor air pollution is second-hand smoke.

Currently, millions of people in the UK are exposed to second-hand smoke. For children most of this exposure occurs in their own homes. Second-hand smoke increases the risk of cancer and other diseases, such as heart disease and stroke, leading to thousands of deaths every year.

What can I do?

If you are a smoker, smoking outside can help reduce exposure for others in your home. And quitting will have benefits for both your health and theirs.

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